add yaml

yaml_test.go

@@ -43,6 +43,17 @@ func TestKeysDFS(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
+			for j := range c.want {
+				found := false
+				for i := range got {
+					if fmt.Sprint(got[i]) == fmt.Sprint(c.want[j]) {
+						found = true
+					}
+				}
+				if !found {
+					t.Errorf("want %+v among %+v", c.want[j], got)
+				}
+			}
 			if fmt.Sprintf("%+v", got) != fmt.Sprintf("%+v", c.want) {
 				t.Fatalf("want: %+v\ngot: %+v", c.want, got)
 			}